This invention relates to a fuel injector valve seat assembly in general, and more particularly, to a fuel injector valve seat assembly with radially outward leading fuel flow passages feeding a multi-hole orifice disk.
Most modern automotive fuel systems utilize fuel injectors to provide precise metering of fuel for introduction into each combustion chamber. Additionally, the fuel injector atomizes the fuel during injection, breaking the fuel into a large number of very small particles, increasing the surface area of the fuel being injected, and allowing the oxidizer, typically ambient air, to more thoroughly mix with the fuel prior to combustion. The precise metering and atomization of the fuel reduces combustion emissions and increases the fuel efficiency of the engine.
An electro-magnetic fuel injector typically utilizes a solenoid assembly to supply an actuating force to a fuel metering valve. Typically, the fuel metering valve is a plunger-style needle valve which reciprocates between a closed position, where the needle is seated in a valve seat to prevent fuel from escaping through a metering orifice into the combustion chamber, and an open position, where the needle is lifted from the valve seat, allowing fuel to discharge through the metering orifice for introduction into the combustion chamber.
Typically, a volumetric chamber or sac exists downstream from the discharge tip of the needle and upstream of the orifice. Upon seating of the needle on the valve seat, a volume of fuel, in liquid form, remains within the sac volume, typically during low manifold pressure, at low or ambient tip temperature operating conditions such as during a cold-start. At high temperature, such as during a hot-start, this volume of fuel tends to be in vapor form which leads to difficult starting as this volume would cause the fuel mixture to be richer than anticipated by a fuel injection controller during such a hot-starting operation. Similarly, during a hot shut-down, some of the fuel, however, remains in the sac which vaporizes due to heat soak and causes evaporative emissions which are undesirable. Thus, in order to minimize the amount of fuel in the sac volume that can be vaporized between hot and cold starts, it is believed that this sac volume should be minimized.
It is believed that some existing fuel injectors employ a valve seat assembly with a centerline through-hole that feeds directly to an orifice disk via a fairly large sac volume. In addition to the disadvantages described above, it is believed that this large sac volume creates vortices. The growth and decay of both inner and outer vortices result in spray instability, which is detrimental to spray definition, i.e., targeting. Furthermore, the existing single centerline through-hole limits the size of a diameter of a bolt circle. Thus, it is believed that a fuel injector valve seat assembly is needed that can control delivery of fuel while maintaining current sealing diameters, minimizing sac volume, and eliminating vortex generation.
The present invention provides a fuel injector for use in a fuel injection system of an internal combustion engine that minimizes sac volume and tends to reduce undesirable vortices in the flow of fuel. In one preferred embodiment of the invention, the fuel injector includes a body, a valve seat, a closure member, an orifice plate, and a metering device. The body has an inlet, an outlet, and a longitudinal axis entering therethrough. The valve seat is disposed proximate the outlet and has a first surface and a second surface. The valve seat includes a valve seat orifice disposed between the first and second surfaces. The closure member is movable along the longitudinal axis between a first position occluding fuel flow and a second position permitting fuel flow through the valve seat orifice. The closure member and the valve seat define a sealing surface in the first position of the closure member. The sealing surface is located on a virtual circle that defines a sealing diameter. The orifice plate is disposed proximate the outlet and has a third surface and a fourth surface. The orifice plate includes at least one orifice disposed between the third and fourth surfaces. The at least one orifice is located on a virtual circle on the orifice plate that defines a first diameter. The metering device is located between the valve seat and the orifice plate. The metering device has a first face and a second face contiguous to a third face. At least one of the first and third faces are spaced from one of the first and second surfaces of the valve seat to define a plurality of passages. Each passage has an inlet to the passage and an outlet from the passage. The outlet of each passage is located on a virtual circle that defines a second diameter greater than at least one of the first diameter and the sealing diameter.
The present invention also provides a flow diverter for a fuel injector that tends to reduce flow vortices and maintain spray stability. In another preferred embodiment of the invention, the flow diverter includes a valve seat, an orifice plate, and an insert. The valve seat is disposed along a longitudinal axis and has a first surface and a second surface. The valve seat further includes a valve seat orifice located between the first surface and the second surface and defines an orifice diameter with respect to the longitudinal axis. The orifice plate is disposed on the longitudinal axis and has at least two orifices. Each orifice of the at least two orifices are located at a first diameter from the other orifice. The insert is disposed along the longitudinal axis between the valve seat and the orifice plate. The insert has an annular portion coupled to a main portion, which protrudes into the valve seat orifice. The main portion has a first face spaced from one of the first and second surfaces of the valve seat to define at least two passageways. Each of the at least two passageways are contiguous to at least one virtual circle defining a second diameter. The second diameter is greater than the first diameter.
The present invention further provides a method of directing the flow of a fuel injector that maintains spray stability of the fuel exiting the fuel injector. In one preferred embodiment, the fuel injector has a body with a first end and a second end disposed along a longitudinal axis. A valve seat is disposed proximate the second end and has a first surface and a second surface, the second surface disposed about the longitudinal axis to define a valve seat orifice. A closure member movable along the longitudinal axis between a first position blocking fuel flow through the valve seat and a second position permitting fuel flow through the valve seat, the closure member defining, in the first position, a sealing diameter on the first surface of the valve seat. An orifice plate located proximate the second end, the orifice plate having at least two orifices located on a virtual circle defining a first diameter, and a metering device having an annular portion coupled to a main portion, the main portion having a first face and a second face, the first face projecting into the valve seat orifice and being spaced from the second surface of the valve seat to define at least one passage between the main portion and the second surface of the valve seat. In the preferred embodiment, the method can be achieved by directing fuel through the at least one passageway having a portion disposed on a virtual circle defining a second diameter greater than at least one of the first diameter and the sealing diameter; causing the fuel to flow towards the longitudinal axis; and diverting the fuel through the at least one orifice of the orifice plate.